The invention relates to circuits for providing alternating current excitation waveforms for transducers used in material testing and other applications.
Alternating current (AC) excitation has been employed with electronic transducers such as strain gauges to reduce noise (which typically is higher at lower frequencies and can be cancelled out) and drift (which typically is direct current). Some transducers, such as LVDTs, require AC excitation.
In material testing load frames used to measure stress and strain of samples, AC excitation has typically been implemented by analog oscillators with analog components. Analog components have also typically been used for demodulation of the transducer's signal, for filtering, and for ranging, a technique used to obtain better accuracy and dynamic range. Potentiometers were used for circuit alignment.